Looking to put a different hand guard on my Ruger. I just want to lose the quad rail and just have the single rail on top. Is there any aftermarket handguards for the SR556? I cannot seem to find any. Thanks

You might call Ruger and see if they'll sell you one from their Varmint Target model.
I think it's smooth-sided. 20" barrel though, so if it's a longer handguard, it won't work.
Check the Ruger forums, too. I'll bet someone has tried something else.

The handguard is proprietary.

Soo there isn't anything out there then?

Pretty much no, along with all the rest of their proprietary parts on the gun.

That is one of the big reason why I eventually sold my SR-556s and switched over to using Adams Arms.  Now, if I break something, simply want an extra of something, or whatever, I simply load up Adams Arms' website, add said part(s) to cart and check out.

For example, if something breaks (which nothing has yet), I can 100% deal with it myself rather than dealing with hassle of having to ship the damn gun back to the factory (in Ruger's case) and hassle with their warranty dept. about this issue or that issue.

Adams Arms has about as "open" of a system as you can get, in terms of parts availability and their willingness to support the customer by selling individual parts directly to the customer when they want/need them.

And lastly, there are a number of 3rd party handguards that also work with their system.

I take it you haven't had much experience with Ruger's customer service.  

No argument from me on their use of a propriety front end.  I'm actually surprised Samson or MI or someone similar isn't making a Keymod or M-LOK aftermarket replacement.  I think they'd have a market if they did.

Yeah, I never did have a problem with either of mine while I had them, so I do give them credit for that.  But, I never did like the idea of having to send serialized parts off to have them serviced if/when a problem arose -- regardless of the severity, or lack thereof of the problem.

I don't think Ruger has ever sold bolts or barrels or parts that could be incorrectly fitted and installed.  I believe the policy is they won't sell anything that could result in incorrect headspace or an otherwise unsafe weapon.  That policy might make some sense with an M77 or a Mini-14 but it really shouldn't apply to the SR556.  Even so, that shouldn't really deter anyone from buying an SR-556 since the bolt, firing pin, extractor, etc are standard M16 pattern and can be bought just about anywhere.

In addition to my surprise with the lack of aftermarket support, I am equally surprised that Ruger doesn't offer a "field repair kit" on the shop Ruger website.  I wouldn't think it would be a bad idea to sell a small kit containing an extra gas regulator, piston, etc.

The gas block not only just makes up the front part of the rail/handguard, but also houses the op-rod tube.  I think this may be why no-one is making handguards for them.

As stated before, the handguard from the other model may work and fits the criteria you stated.

http://fortismfg.com/ar15-fortis-REV-free-float-rail-system-mid-cutout

this is the closest i've found as a replacement. but, i can't say for sure if it will. i've tried emailing fortis for proper specs on the handguard w/o any answer. even if i had the money, i'm just not willing enough to spend it to find out for myself. if i could find the inner diameter and the weight of the SR handguard, it would help in making the decision to finally call fortis and just ask a service representative.

This is why I ended up selling my SR556.  Thing was accurate as hell and was a tank, but damn it was heavy and I wanted to change the hand guard.  It pissed me off to no end that they pinned the troy hand guard to the gun.  It was the first AR I ever owned, so lesson learned.